Conferencing systems allow participants of a conference at one location to interact with participants of the conference at another location. A conferencing system typically includes at least a microphone at each location and a speaker at each location, where the microphone and the speaker at each location may be combined within a single device. The system may further include a video camera at each location and a display at each location, where videoconferencing is to be achieved instead of just simply audio conferencing or teleconferencing.
Before sound detected by a microphone at a first location is transmitted to a second location for emission by the speaker at the second location, echo cancellation is usually performed. Echo cancellation at the first location, for instance, involves at least substantially suppressing or removing any sound detected by the microphone at the first location that was emitted by a speaker at the first location, where such sound is that which was recorded by a microphone at the second location. Echo cancellation at the second location is typically performed in a similar manner. If echo cancellation is not performed, participants at the first location may hear their own voices from the speaker at their location, and likewise participants at the second location may hear their own voices from the speaker at their location, which can be unsettling.
Echo cancellation is usually performed well where there is just a single microphone and a single speaker at each location. However, more sophisticated conferencing systems can in particular include multiple speakers at each location. In such situations, echo cancellation is more difficult to achieve. For instance, echo cancellation may have to be performed for each speaker in relation to each microphone, or more generally for each sound source signal distributed among the speakers, in relation to each microphone. So-called multiple-channel echo cancellation can require relatively expensive and difficult-to-set-up equipment, however, which serves to limit widespread deployment of such more sophisticated conferencing systems.